Souissi Imen Jguirim, Billiet Ludivine, Cuaz-Pérolin Clarisse, Slimane Mohamed-Naceur, Rouis Mustapha
Research Laboratory on Atherosclerotic Biological and Genetic Factors, Faculty of Medicine, Monastir TN-5019, Tunisia.
Exp Cell Res. 2008 Nov 1;314(18):3405-14. doi: 10.1016/j.yexcr.2008.09.002. Epub 2008 Sep 18.
MMP-12, a macrophage-specific matrix metalloproteinase with large substrate specificity, has been reported to be highly expressed in mice, rabbits and human atherosclerotic lesions. Increased MMP-12 from inflammatory macrophages is associated with several degenerative diseases such as atherosclerosis. In this manuscript, we show that IL-1beta, a proinflammatory cytokine found in atherosclerotic plaques, increases both mRNA and protein levels of MMP-12 in human monocyte-derived macrophages (HMDM). Since peroxisome proliferator-activated receptors (PPARs), such as PPARalpha and PPARgamma, are expressed in macrophages and because PPAR activation exerts an anti-inflammatory effect on vascular cells, we have investigated the effect of PPARalpha and gamma isoforms on MMP-12 regulation in HMDM. Our results show that MMP-12 expression (mRNA and protein) is down regulated in IL-1beta-treated macrophages only in the presence of a specific PPARalpha agonist, GW647, in a dose-dependent manner. In contrast, this inhibitory effect was abolished in IL-1beta-stimulated peritoneal macrophages isolated from PPARalpha(-/-) mice and treated with the PPARalpha agonist, GW647. Moreover, reporter gene transfection experiments using different MMP-12 promoter constructs showed a reduction of the promoter activities by approximately 50% in IL-1beta-stimulated PPARalpha-pre-treated cells. However, MMP-12 promoter analysis did not reveal the presence of a PPRE response element. The IL-1beta effect is known to be mediated through the AP-1 binding site. Mutation of the AP-1 site, located at -81 in the MMP-12 promoter region relative to the transcription start site, followed by transfection analysis, gel shift and ChIP experiments revealed that the inhibitory effect was the consequence of the protein-protein interaction between GW 647-activated PPARalpha and c-Fos or c-Jun transcription factors, leading to inhibition of their binding to the AP-1 motif. These studies suggest that PPARalpha agonists may be used therapeutically, not only for lipid disorders, but also to prevent inflammation and atheromatous plaque rupture, where their ability to inhibit MMP-12 expression in HMDM may be beneficial.
基质金属蛋白酶-12（MMP-12）是一种具有广泛底物特异性的巨噬细胞特异性基质金属蛋白酶，据报道在小鼠、兔子和人类动脉粥样硬化病变中高度表达。炎症巨噬细胞中MMP-12的增加与动脉粥样硬化等几种退行性疾病有关。在本论文中，我们表明白细胞介素-1β（IL-1β），一种在动脉粥样硬化斑块中发现的促炎细胞因子，可增加人单核细胞衍生巨噬细胞（HMDM）中MMP-12的mRNA和蛋白质水平。由于过氧化物酶体增殖物激活受体（PPARs），如PPARα和PPARγ，在巨噬细胞中表达，且PPAR激活对血管细胞具有抗炎作用，我们研究了PPARα和γ亚型对HMDM中MMP-12调节的影响。我们的结果表明，仅在存在特异性PPARα激动剂GW647的情况下，IL-1β处理的巨噬细胞中MMP-12的表达（mRNA和蛋白质）以剂量依赖的方式下调。相反，在从PPARα（-/-）小鼠分离并用PPARα激动剂GW647处理的IL-1β刺激的腹膜巨噬细胞中，这种抑制作用被消除。此外，使用不同MMP-12启动子构建体的报告基因转染实验表明，在IL-1β刺激的PPARα预处理细胞中，启动子活性降低了约50%。然而，MMP-12启动子分析未发现PPRE反应元件的存在。已知IL-1β的作用是通过AP-1结合位点介导的。对位于MMP-12启动子区域相对于转录起始位点-81处的AP-1位点进行突变，随后进行转染分析、凝胶迁移和染色质免疫沉淀实验表明，抑制作用是GW 647激活的PPARα与c-Fos或c-Jun转录因子之间蛋白质-蛋白质相互作用的结果，导致它们与AP-1基序的结合受到抑制。这些研究表明，PPARα激动剂不仅可用于治疗脂质紊乱，还可用于预防炎症和动脉粥样斑块破裂，其在HMDM中抑制MMP-12表达的能力可能是有益的。
